Radio receiving system



y 6, 1943- A. LE R. UPTON 2,323,858

RADIO RECEIVING SYSTEM Filed July 31, 1942 katented July 6, 1943 UNITEDSTATES PATENT OFFICE aamo nacarvmc SYSTEM v Albert Le Roy Upton, St.Louis, Mo. Application July 31, 1942, Serial No. 453,124

3 Claims. (01.179-1) This invention relates to radio receivers.

An object of the invention is to provide means whereby anaudio-frequency circuit in a receiver may be used simultaneouslyorselectively to actuate a loud speaker and actuate a secondary circuitfor the purpose of producing a recording, operating a public addresssystem or rebroadcast. That is to say, a monitor loud speaker may beused to receive a radio broadcast, and then by manipulation theactuating circuit for the loud speaker can, at the will of the operator,influence a secondary circuit for-the purposes indicated. Thearrangement is such that the loud speaker may be cut out, if desired,and when out out the operation is quiet. These objects and theconstruction and operation of the system will be apparent from thefollowing detailed description taken in connection with the accompanyingdrawing.

The drawing is a circuit diagram of a system embodying the invention.

The speaker circuit I includes the secondary coil 2 of a transformer 8,the voice coil 4 of a loud speaker, and the primary coil 5 of atransformer 6. The primary I of the transformer 3 is in a circuit froman audio amplifier. It will be understood that the arrangement asdescribed, apart from the transformer 8 and its primary 5, is ofconventional design and is such as is commonly used in radio receivers.By reason, however, of the transformer 6 in the circuit i this circuitis used to operate a remote public address system, a recorder, or as aninput for a rebroadcast.

The coils 2, 4 and 5 are matched. As an example, each may have aninductance of 2 ohms. For theoretical ideal operating conditions oneonly of the coils i and 5 will be in the circuit effectively at a time,but practically both of them can be in circuit simultaneously withoutaffecting the results.

A three-way switch 8 is operable to by-pass either coil 4 or 5selectively at will. Thus when the switch is closed on terminal 9 thevoice coil 4 is by-passed, but when it is closed on the terminal ill thecoil 6 is by-passed. When the switch is in neutral position ll, bothcoils l and 5 are in circuit.

The secondary of the transformer 6 is in a circuit I2 which alsoincludes the primary of a transformer l3. In this circuit the secondaryof the transformer 6, and the primary of the transformer I3, arematched.

The secondary of the transformer I3 is in a circuit It supplying theinput for a recorder or pre-amplifier, whereby signals carried by thecircuit I may be used for secondary, public address or rebroadcast.

The coils of the transformer 8 and I which are in the circuit I! shouldhave matched impedance.

A jack l5 across the circuit l2 accommodates a plug l6 connected to avisual indicator H, by which the amplitude of the signal can be read.

A contant impedance attenuator I8 is placed across the circuit I4, bywhich the amplitude of the. signal fed through that circuit may becontrolled.

In using the system, the speaker can be employed as a monitor. When thebroadcast is first received through the speaker the switch I will beclosed on the terminal l0, shunting the coil 5. Then when the receptionindicates it should be relayed to the remainder of the system, theswitch is moved to the terminal I or neutral position II. If it isdesired to retain the speaker in service, the switch will be moved toneutral position, by which the speaker coil 4 and the transformer coil 5will be in series. Even though theoretically this is not the idealcondition, satisfactory service is obtained. For perfect performance,however, the switch is moved to the terminal 9, shunting the coil 4, assoon as the speaker can be eliminated. Because of the arrangement of theswitch 8 in the circuit, with its three positions as shown, it can bemoved from any position to the other without any audible click either inthe speaker or the auxiliary part of the system.

The circuit i4 may feed any desired reproduction system, as for instancea theatre sound system illustrated and described in my copendingapplication filed on the same date herewith.

It will be obvious that various changes may be made in the details ofconstruction, within the scope of the appended claims, without departingfrom the spirit of this invention. Parts of the invention may be usedwithout the whole and improvements and additions may be made theretowhile retaining the essence of the invention.

I claim:

1. In a radio receiver, a circuit fed from an audio amplifier, a speakercircuit connected with the first mentioned circuit through a transformerhaving a primary coil in the first mentioned circuit and a secondarycoil in the speaker circuit, a voice coil for a speaker and a primarycoil of a second transformer in series in said speaker circuit with theaforementioned secondary coil, a switch arranged to selectively by passeither said voice coil or said primary coil of the second transformer,and a feed circuit for a reproduction system including a, secondary coilof said second transformer.

2. In a radio receiver, a circuit fed from an audio amplifier, a speakercircuit connected with the first mentioned circuit through a transformerhaving a primary coil in the first mentioned circuit and a secondarycoil in the speaker circuit, a voice coil for a speaker and a primarycoil by a second transformer in series in said speaker circuit with theaforementioned secondary coil, a feed circuit for a reproduction system,including a secondary coil of said second transformer,

and a. constantimpedance attenuator for controlling the amplitude of thesignals from said feed circuit.

3. In a radio receiver, a circuit fed from an audio amplifier, a speakercircuit connected with the first mentioned circuit through a transformerhaving a primary. coil in the first mentioned circuit and a secondarycoil in the speaker circuit. a voice coil for a speaker and a primarycoil by a second transformer in series in said speaker circuit with theaforementioned secondary coil, a feed circuit for a reproduction systemincluding a secondary coil of said second transformer, and a visualindicator in the feed circuit by which the amplitude of the signals insaid circuit may be read.

ALBERT LE ROY UPTON.

